Submission #1049226

#	Time	Username	Problem	Language	Result	Execution time	Memory
1049226		khanhtb	Valley (BOI19_valley)	C++14	0 / 100	109 ms	225732 KiB

valley

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define ld long double
#define pb push_back
#define pf push_front
#define vi vector<ll>
#define vii vector<vi>
#define pll pair<ll, ll>
#define vpll vector<pll>
#define all(a) a.begin(), a.end()
#define fi first
#define se second
using namespace std;
const ll mod = 1e9+7; 
const ll inf = 2e18;
const ll B = 320;
const ll N = 6e5+8;
int n,s,q,e;
vector<pair<int,ll>> g[N];
vector<pair<int,int>> edge = {{0,0}};
bool mark[N];
int tin[N],tout[N],tdfs,d[N],h[N],arr[N];
void dfs_shop(int u, int p){
    tin[u] = ++tdfs;
    arr[tdfs] = u;
    for(pair<int,ll> ed:g[u]){
        int v = ed.fi;
        ll w = ed.se;
        if(v == p) continue;
        d[v] = d[u]+w;
        h[v] = h[u]+1;
        dfs_shop(v,u);
    }
    tout[u] = tdfs;
}
ll st[20][N],a[N];
void build(){
    for(int i = 1; i <= n; i++) st[0][i] = (mark[arr[i]]?d[arr[i]]:inf);
    for(int j = 1; j < 20; j++){
        for(int i = 1; i + (1<<j) - 1 <= n; i++){
            st[j][i] = min(st[j-1][i],st[j-1][i+(1<<(j-1))]);
        }
    }
}
ll rmq(int l, int r){
    int k = __lg(r-l+1);
    return min(st[k][l],st[k][r-(1<<k)+1]);
}
struct node{
    int pr;
    ll mn = inf;
} up[N][20];
void dfs_pre(int u, int p){
    for(pair<int,ll> ed:g[u]){
        int v = ed.fi;
        if(v == p) continue;
        up[v][0].pr = u;
        up[v][0].mn = min(a[u]-2*d[u],a[v]-2*d[v]);
        for(int i = 1; i <= 19; i++){
            up[v][i].pr = up[up[v][i-1].pr][i-1].pr;
            up[v][i].mn = min(up[v][i-1].mn,up[up[v][i-1].pr][i-1].mn);
        }
        dfs_pre(v,u);
    }
}
bool is_anc(int u, int v){
    return tin[u] <= tin[v] && tout[v] <= tout[u];
}
ll query(int u, int p){
    int k = h[u]-h[p];
    ll ans = inf;
    for(int i = 19; i >= 0; i--){
        if(k>>i&1){
            ans = min(ans,up[u][i].mn);
            u = up[u][i].pr;
        }
    }
    ans = min(ans,a[u]);
    return ans;
}
void solve(){
    cin >> n >> s >> q >> e;
    for(int i = 1; i < n; i++){
        int u,v;
        ll w;cin >> u >> v >> w;
        g[u].pb({v,w});
        g[v].pb({u,w});
        edge.pb({u,v});
    }
    for(int i = 1; i <= s; i++){
        int x;cin >> x;
        mark[x] = 1;
    }
    dfs_shop(e,e);
    build();
    for(int i = 1; i <= n ;i++) a[i] = rmq(tin[i],tout[i]);
    dfs_pre(e,e);
    while(q--){
        int id,r;cin >> id >> r;
        int u;
        if(h[edge[id].fi] > h[edge[id].se]) u = edge[id].fi;
        else u = edge[id].se;
        if(!is_anc(u,r)) cout << "escaped\n";
        else{
            ll ans = query(r,u)+d[r];
            if(ans >= 1e14) cout << "oo\n";
            else cout << ans << '\n';
        }
    }
}
signed main(){
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    if (fopen("test.inp", "r")) {
        freopen("test.inp", "r", stdin);
        freopen("test.out", "w", stdout);
    }   
    ll T = 1;
    // cin >> T;
    for (ll i = 1; i <= T; i++) {
        solve();
        // cout << '\n';
    }
}

Compilation message (stderr)

valley.cpp: In function 'int main()':
valley.cpp:115:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  115 |         freopen("test.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:116:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  116 |         freopen("test.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 9
• Subtask 2: 0 / 27
• Subtask 3: 0 / 23
• Subtask 4: 0 / 41